Set-reset latches

Abstract

Examples disclosed herein relate to set-reset (SR) latch circuits and methods for manufacturing the same. In some of the disclosed examples, a SR latch circuit includes an inverter storage loop for storing state information and a set of p-channel field-effect transistors (PFETs) for control circuitry. The PFETs may include first and second PFETs connected to a first node of the inverter storage loop, and third and fourth PFETs connected to a second node of the inverter storage loop. Gate terminals of the first and fourth PFETs may be connected to a first control input, and gate terminals of the second and third PFETs may be connected to a second control input.

The invention claimed is: 
     
       1. A circuit, comprising:
 an inverter storage loop for storing state information; 
 first and second p-channel field-effect transistors (PFETs) connected to a first node of the inverter storage loop; and 
 third and fourth PFETs connected to a second node of the inverter storage loop; 
 wherein gate terminals of the first and fourth PFETs are connected to a first control input, and gate terminals of the second and third PFETs are connected to a second control input. 
 
     
     
       2. The circuit of  claim 1 , wherein:
 a drain terminal of the first PFET and a source terminal of the second PFET are connected to the first node of the inverter storage loop; and 
 a drain terminal of the third PFET and a source terminal of the fourth PFET are connected to the second node of the inverter storage loop. 
 
     
     
       3. The circuit of  claim 2 , wherein:
 a source terminal of the first PFET and a source terminal of the third PFET are connected to a voltage source; and 
 a drain terminal of the second PFET and a drain terminal of the fourth PFET are connected to a voltage drain. 
 
     
     
       4. The circuit of  claim 1 , wherein:
 the first control input is a Set control input; and 
 the second control input is a Reset control input. 
 
     
     
       5. The circuit of  claim 4 , wherein the Set and Reset control inputs are active low control inputs. 
     
     
       6. The circuit of  claim 1 , wherein the circuit is implemented in a 16 nm process. 
     
     
       7. The circuit of  claim 1 , wherein the inverter storage loop includes a cross-coupled first inverter and second inverter. 
     
     
       8. The circuit of  claim 7 , wherein the cross-coupled first inverter and second inverter each include a PFET and an n-channel field-effect transistor (NFET). 
     
     
       9. The circuit of  claim 1 , wherein an output at the first node is a Set latch output and an output at the second node is a Reset latch output. 
     
     
       10. The circuit of  claim 1 , comprising:
 a fifth PFET connected between the first PFET and a voltage source; 
 a sixth PFET connected between the third PFET and the voltage source; 
 a first n-channel field-effect transistor (NFET) connected between the second PFET and a voltage drain; and 
 a second NFET connected between the fourth PFET and the voltage drain; 
 wherein gate terminals of the fifth and sixth PFETs are connected to an Enable B multiplexer control input and gate terminals of the first and second NFETs are connected to an Enable multiplexer control input. 
 
     
     
       11. The circuit of  claim 10 , wherein the inverter storage loop is a first inverter storage loop, the circuit comprising:
 a second inverter storage loop for storing state information; 
 seventh and eighth PFETs connected to a first node of the second inverter storage loop, a gate terminal of the seventh PFET being connected to the first control input and a gate terminal of the eighth PFET being connected to the second control input; 
 ninth and tenth PFETs connected to a second node of the second inverter storage loop, a gate terminal of the ninth PFET being connected to the second control input and a gate terminal of the tenth PFET being connected to the first control input; 
 an eleventh PFET connected between the seventh PFET and the voltage source; 
 a twelfth PFET connected between the ninth PFET and the voltage source; 
 a third NFET connected between the eighth PFET and the voltage drain; and 
 a fourth NFET connected between the tenth PFET and the voltage drain; 
 wherein gate terminals of the eleventh and twelfth PFETs are connected to the Enable multiplexer control input and gate terminals of the third and fourth NFETs are connected to the Enable B multiplexer control input; and 
 wherein the first node of the first inverter storage loop is connected to the first node of the second inverter storage loop and the second node of the first inverter storage loop is connected to the second node of the second inverter storage loop. 
 
     
     
       12. A set-reset (SR) latch, comprising:
 an inverter storage loop for storing state information; 
 first and second n-channel field-effect transistors (NFETs) connected to a first node of the inverter storage loop; and 
 third and fourth NFETs connected to a second node of the inverter storage loop, 
 wherein gate terminals of the first and fourth NFETs are connected to a first control input, and gate terminals of the second and third NFETs are connected to a second control input. 
 
     
     
       13. The SR latch of  claim 12 , wherein:
 the first control input is a Set control input; and 
 the second control input is a Reset control input. 
 
     
     
       14. The SR latch of  claim 13 , wherein the Set and Reset control inputs are active high control inputs. 
     
     
       15. A method for manufacturing a set-reset (SR) latch, comprising:
 forming an inverter storage loop for storing state information; 
 forming first and second p-channel field-effect transistors (PFETs) connected to a first node of the inverter storage loop; 
 forming third and fourth PFETs connected to a second node of the inverter storage loop; 
 connecting gate terminals of the first and fourth PFETs to a first control input; and 
 connecting gate terminals of the second and third PFETs to a second control input. 
 
     
     
       16. The method of  claim 15 , wherein the inverter storage loop and the first, second, third, and fourth PFETs are formed using a 16 nm process. 
     
     
       17. The method of  claim 16 , wherein forming the inverter storage loop includes:
 forming a cross-coupled first inverter and second inverter, the cross-coupled first inverter and second inverter each including a PFET and an n-channel field-effect transistor (NFET). 
 
     
     
       18. The method of  claim 15 , wherein:
 the first control input is a Set control input; and 
 the second control input is a Reset control input.